Fix residual breakage from Windows socket-errno patch: the routines

that should use regular errno, not WSAGetLastError(), now do so again.

src/interfaces/libpq/win32.h

@@ -7,7 +7,7 @@
 #define strncasecmp(a,b,c) _strnicmp(a,b,c)
 
 /*
- * Some compat functions
+ * Some other compat functions
  */
 #define open(a,b,c) _open(a,b,c)
 #define close(a) _close(a)
@@ -21,18 +21,20 @@
 /*
  * crypt not available (yet)
  */
-#define crypt(a,b) a
+#define crypt(a,b) (a)
 
 /*
- * assumes that errno is used for sockets only
- *
+ * Most of libpq uses "errno" to access error conditions from socket calls,
+ * so on Windows we want to redirect those usages to WSAGetLastError().
+ * Rather than #ifdef'ing every single place that has "errno", hack it up
+ * with a macro instead.  But there are a few places that do need to touch
+ * the regular errno variable.  For them, we #undef and then redefine errno.
  */
 
-#undef errno
-#undef EINTR
-#undef EAGAIN	/* doesn't apply on sockets */
-
 #define errno WSAGetLastError()
+
+#undef EAGAIN	/* doesn't apply on sockets */
+#undef EINTR
 #define EINTR WSAEINTR
 #define EWOULDBLOCK WSAEWOULDBLOCK
 #define ECONNRESET WSAECONNRESET